The scale
PA+ to PA++++, band by band
PA comes from the Japanese standard and is graded on PPD — Persistent Pigment Darkening. Testers apply 2 mg/cm² of product, expose the skin to UVA, and measure how many times longer it takes for lasting tanning to appear. A PPD of 8 means eight times longer.
- PA+PPD 2 to under 4
Minimal UVA protection. Rare on modern formulas.
- PA++PPD 4 to under 8
Moderate. Fine for a mostly-indoor day.
- PA+++PPD 8 to under 16
High. The sensible everyday baseline.
- PA++++PPD 16 or higher
Very high. What you want for long days outside.
Other systems
UVA-in-a-circle, boots stars, and 'broad spectrum'
The EU UVA circle is a pass/fail mark: UVA protection must be at least one third of the labelled SPF. On an SPF 50 that implies a UVA-PF of about 17, which lands around PA++++ — but it's a floor, not a grade, so you learn nothing about how far above it a product sits.
The Boots star rating (UK) is a ratio, not an absolute. Five stars on an SPF 15 is weaker UVA protection than four stars on an SPF 50, which trips up a lot of shoppers.
In practice
What rating do you actually need?
For daily life in a city, PA+++ is a reasonable baseline. For a beach day, a hike, or anything at altitude or on water, go PA++++ and reapply every two hours regardless of what the number says.
The bigger variable is dose. Almost everyone applies between a quarter and a third of the tested amount, and protection falls off faster than linearly — so an under-applied PA++++ can behave like PA++. Two fingers' length for the face and neck, and again after two hours outdoors, moves the needle far more than trading one plus sign for another.
Filters matter too. Strong UVA coverage generally comes from Tinosorb S/M, Uvinul A Plus, Mexoryl SX/XL or a high load of zinc oxide. A formula built on older filters can hit SPF 50 while leaving a visible UVA gap.
Caveats
Where the number stops being useful
PA is measured in a lab on a flat, evenly coated patch of skin. Sweat, rubbing, sebum and a moving face all erode it. Water-resistance claims describe a 40- or 80-minute immersion test, not a whole day.
And a label is a claim, not a measurement of your bottle. Independent testing has repeatedly found products that miss their stated SPF. That's exactly why we cross-check filter systems and, where they exist, published lab reports — see How we know this.
Free tools & guides
No sign-up.
- ToolIngredient decoderPaste an INCI list and see what each ingredient actually does.
- ToolPore clogger checkerFind the comedogenic ingredients, weighted by list position.
- ToolFungal acne checkerSpot the ingredients malassezia yeast can feed on.
- ToolPregnancy ingredient checkerScreen a formula for ingredients commonly avoided in pregnancy.
Early access
We read the filter system, not the marketing
Skinparency scores UVA protection from the actual filters in the formula — plus whitecast, stickiness and eye sting from people who wore it.
Free to join · no spam · one launch email